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Multimedia Systems. Lecture - 12. OUTLINE. MPEG Standards (continued). MPEG Overview ( Recap ). MPEG is the name of a family of standards used for coding audio-visual information (e.g., movies, video, music) in a digital compressed format.

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multimedia systems

Multimedia Systems

Lecture - 12

  • MPEG Standards (continued)
mpeg overview recap
MPEG Overview (Recap)
  • MPEG is the name of a family of standards used for coding audio-visual information (e.g., movies, video, music) in a digital compressed format.
  • As compared to other video and audio coding formats, MPEG files are much smaller for the same quality.
  • MPEG standards include MPEG-1, MPEG-2, MPEG-3, MPEG-7, and so on.
mpeg 2
  • MPEG-2 is broader in scope and wider in appeal as compared to its predecessor.
  • It supports higher video quality and higher data rate (up to 80 Mbits/sec)
  • MPEG-2 is widely used as the format for over-the-air digital television signals broadcasting, cable TV, and digital satellite TV systems.
mpeg 21
  • It also specifies the format of movies and other programs that are distributed on DVD and similar discs (e.g., Blu-ray discs).
  • It supports interlacing and high definition.
mpeg 2 parts
MPEG-2 Parts
  • MPEG-2 standard was published as Parts of ISO/IEC 13818.
    • Part 1
      • Systems – describes synchronization (timing info) and multiplexing of video and audio
    • Part 2
        • Video – specifies compression codec for interlaced and non-interlaced video signals (Also known as H.262).
    • Part 3
      • Audio – specifies compression codec for perceptual coding of audio signals.
      • Also called MPEG-2 BC; backward compatible with MPEG-1 audio decoders
    • Other Parts include Part 4, 5, 6, 7, 9, 10, 11. Part 8 was withdrawn.
mpeg 2 frame types
MPEG-2 Frame Types
  • MPEG-2 specifies that the raw frames be compressed into three kinds of frames:
    • intra-coded frames (I-frame),
    • predictive-coded frames (P-frames), and
    • bidirectionally-predictive-coded frames (B-frames).
mpeg 2 frame types1
MPEG-2 Frame Types
  • An I-frame is a compressed version of a single uncompressed (raw) frame. It takes advantage of spatial redundancy and of the inability of the eye to detect certain changes in the image.
  • P-frames provide more compression than I-frames because they take advantage of the data in a previous I-frame or P-frame (a reference frame).
mpeg 2 frame types2
MPEG-2 Frame Types
  • B-frames’ processing is similar to that of P-frames except that B-frames use the picture in a subsequent reference frame as well as the picture in a preceding reference frame. As a result, B-frames usually provide more compression than P-frames.
mpeg 2 typical frame sizes
MPEG-2 Typical frame sizes
  • I-frame: 400,000 bits
  • P-frame: 200,000 bits
  • B-frame: 80,000 bits
mpeg 2 profiles levels
MPEG-2 Profiles & Levels
  • MPEG-2 video supports a wide range of applications from mobile to high quality HD editing.
  • For many applications, it is not feasible to support the entire standard. To allow such applications to support only subsets of it, the standard defines profiles and levels.
  • Profile defines the subset of features such as compression algorithm, chroma format, etc.
  • Level defines the subset of quantitative capabilities such as maximum bit rate, maximum frame size, etc.
mpeg 2 profiles levels1
MPEG-2 Profiles & Levels
  • A MPEG application specifies the capabilities in terms of profile and level.
  • For example, a DVD player may say it supports up to main profile and main level (often written as MP@ML).
  • It means the player can play back any MPEG stream encoded as MP@ML or less.
various mpeg 2 profiles levels
Various MPEG-2 Profiles & Levels
  • Profiles
    • Simple profile (SP)
    • Main profile (MP)
    • SNR Scalable profile (SNR)
    • Spatially Scalable profile (Spatial)
    • High Profile (HP)
  • Levels
    • Low Level (LL)
    • Main Level (ML)
    • High 1440 (H-14)
    • High Level (HL)
various mpeg 2 profiles levels1
Various MPEG-2 Profiles & Levels
  • Constraints on levels:
    • High
      • 1920 samples/line (horizontal resolution)
      • 1152 lines/frame (vertical resolution)
      • 60 frames/sec
      • 80 Mbits/s
    • High 1140
      • 1440 samples/line
      • 1152 lines/frame
      • 60 frames/sec
      • 60 Mbits/s
various mpeg 2 profiles levels2
Various MPEG-2 Profiles & Levels
  • Main
    • 720 samples/line
    • 576 lines/frame
    • 30 frames/sec
    • 15 Mbits/s
  • Low
    • 352 samples/line
    • 288 lines/frame
    • 30 frames/sec
    • 4 Mbits/s
mpeg 3
  • MPEG-3 dealt with standardizing scalable and multi-resolution compression.
  • Targeted HDTV applications with sampling dimensions up to 1920 x 1080 x 30 Hz and coded bitrates between 20 and 40 Mbit/sec
  • MPEG-2 was found to scale to these
  • dimensions, so MPEG-3 was dropped/ merged with MPEG-2.
mpeg 4
  • MPEG-4 also referred to as ISO/IEC 14496, is a standard for a group of audio video coding formats and related technologies.
  • Uses of MPEG-4 include
    • compression of AV data for web (streaming media) and CD distribution,
    • voice (telephone, videophone) and
    • broadcast television applications.
mpeg 41
  • MPEG-4 brings improvements to its predecessors by adding features such as:
    • VRML support for 3D rendering,
    • Object-oriented composite files (including audio, video and VRML objects),
    • support for Digital Rights Management and various types of interactivity
mpeg 4 parts
MPEG-4 Parts
  • MPEG-4 is still a developing standard and is divided into a number of parts
    • Part1
      • Systems – describes synch and multiplexing of video and audio
    • Part2
      • Visual – a compression codec for visual data
    • Part3
      • Audio – set of compression codecs for perceptual coding of audio signals
    • Part4 till Part27…
      • Each having its own specifications
mpeg 4 key parts
MPEG-4 Key Parts
  • The key parts to be aware of are
    • MPEG-4 Part2
      • It is a compression codec for visual data (video, still textures, synthetic images, etc.).
      • One of the many "profiles" in Part 2 is the Advanced Simple Profile (ASP).
      • It is a DCT compression standard, similar to previous standards such as MPEG-1 and MPEG-2.
      • Several popular codecs including DivX, Xvid and Nero Digital are implementations of this standard.
mpeg 4 keyparts
MPEG-4 KeyParts
  • H.264/AVC/MPEG-4 Part 10 (Advanced Video Coding)
    • It is a standard for video compression.
    • H.264/AVC is the latest block-oriented motion-compensation-based codec standard developed by the ITU-T Video Coding Experts Group (VCEG) together with the ISO/IEC Moving Picture Experts Group (MPEG), and it was the product of a partnership effort known as the Joint Video Team (JVT).
    • The ITU-T H.264 standard and the ISO/IEC MPEG-4 Part 10 AVC standard are jointly maintained so that they have identical technical content.
mpeg 4 key parts1
MPEG-4 Key Parts
  • H.264 is used in such applications as
    • Blu-ray Disc,
    • videos from YouTube and the iTunes Store,
    • DVB broadcast,
    • direct-broadcast satellite television service,
    • cable television services, and
    • real-time videoconferencing.
    • The CCTV (Close Circuit TV) or Video Surveillance market has included this technology in many products too
recommended further reading
Recommended further reading …
  • MPEG-4 Profiles and Levels